Electrical switch having interlocking cover and casing members



' Oct. 6, 1910 w. R. BAUER 3,532,840

ELECTRICAL SWITCH HAVING INTERLOCKING COVER AND CASING MEMBERS FiledOct. 10, 1967 5 Sheets-Sheet 1 FIG-4 FIG-5 I ,/1

291 v, w m %g 2109A INVENTOR WERNER ROBERT BAUER HIS ATTORNEYS Oct. 6,1970 I 1 w. BAUER 3,532,840

ELECTRICAL SWITCH HAVING INTERL OCKING COVER AND CASING MEMBERS FiledOct. 10. 19s? 3 Sheets-Sheet 2 56 FIG-ll E 4; Io 6, 2 I23 2 I2 38 I f 58I E 5 351/ |2| I 5 l k K EB, 64 66 84 6O 7O 75 88 FIG-8" h I I I 10 7I03 IOS 22 "M 23 BY 2 m woe ' HIS ATTORNEYS h I23 45 FIG-I012; 45 2912INVENTOR' WERNER ROBERT BAUER United States Patent OfiCe 3,532,840Patented Oct. 6, 1970 US. Cl. 20067 19 Claims ABSTRACT OF THE DISCLOSUREThis application discloses a switch, casing, and cover therefor. Thisswitch construction may be made very small. The outer surfaces of thecasing walls and cover may form a substantially rectangular outersurfaced construction of very minute size with only the actuator plungerand terminal connectors extending therefrom. The casing has four sidewalls, with one of said side walls being relatively thick compared tothe three other side walls. This thick side wall receives an electricalconductor rod and conductor bars which have conductor receivingextensions through which the electrical conductors or wires may besecured. The conductor rod is substantially straight inside the casingand the conductor bars have stationary contact elbows inside the casingwhich are alternatively contacted by movable contacts of a switch blade.The switch blade tongues are pivoted in opposite notches in oppositesides of the straight conductor rod. The thick wall also has fasteneropenings for fastening the switch casing and cover to any desiredsupport. The cover also has cover fastener openings aligned with thefastener openings in the thick wall. If desired, the cover may beprovided with a hook construction that may be inserted into a hookreceiving opening in the thick wall.

This application is a continuation-in-part of applicants copendingapplications, Ser. No. 431,107, filed February 8, 1965, now abandoned,and Ser. No. 642,614, filed March 8, 1967, now Pat. No. 3,449,534.

This invention relates to a switch, casing, and cover therefor.

One of the features of this invention includes a cover with a hookconstruciton which may be inserted in a wall of the switch casing in amanner to fasten the cover securely to the casing in an ei-ficient andsimple manner.

Another feature of this invention includes a very small switch, casing,and cover therefor, which may have very small dimensions, and which maybe made with substantially rectangular outer surfaces, if desired.

Another feature of this invention includes a substantially straightcommon terminal rod and two electrically conductor bars, each bar havingan integral contact elbow to be contacted by the movable contacts of aswitch construction, which may include a switch blade with pivot tonguespivoted on opposite sides of the straight conductor rod.

Another feature of this invention includes a casing having a thicksupporting or holding wall which is relatively and substantially thickerthan the three other side walls and the bottom wall to which thick walla cover may be secured in an efficient manner.

Another feature of this invention includes said hook construction with abent portion that may be straightened slightly while the hookconstruction is being inserted in the hook receiving opening to securethe hook in a hook ledge in the hook receiving opening. The hookreceiving opening may extend completely through the casing wall so thata hook straightening bar and/or a hook releasing tool may be inserted inthe opposite uncovered end of the hook receiving opening.

Other features of this invention are apparent from this description, theappended claimed subject matter, and/or the accompanying drawings inwhich:

FIGS. 1 and 2 are respectively top plan and side elevation views of theouter walls of the switch shown in FIGS. 3-12, and made according tothis invention, the views being drawn to actual scale in the applicationdrawings.

FIG. 3 is a perspective view on a somewhat larger scale taken from therear of FIG. 2.

FIG. 4 is a greatly enlarged cross-section taken along the line 44 ofFIG. 1.

FIG. 5 is a cross-section taken along the line 5-5 of FIG. 4.

FIG. 6 is a view somewhat similar to FIG. 5, but with parts in elevationand with the hook construction straightened by the insertion of a bar.

FIG. 7 is a view somewhat similar to FIG. 5 but taken along the line 77of FIG. 4.

FIG. 8 is a transverse cross-section taken along the line 8-8 of FIGS. 4and 7.

FIG. 9 is an inside perspective view of the cover for the casing.

FIG. 10 is a top plan view taken from the line 1010 of FIG. 9.

FIG. 11 is a plan view of the switch blade of FIGS. 4 and 7 before themovable contacts have been secured thereto.

FIG. 12 is a perspective view of the conductor rod and switch blade ofFIGS. 4 and 7.

FIGS. 13 and 14 are views somewhat similar to FIGS. 1 and 2, but showinganother embodiment of the invention.

FIG. 15 is an enlarged cross-section taken along the line 1515 of FIG.13.

FIG. 16 is a view taken along the line 16-16 of FIG. 15.

FIG. 17 is a plan view of the switch blades of FIGS. 15 and 16 beforethe movable contacts have been secured thereto.

FIG. 18 is a view similar to FIG. 17, but showing a diiferentconstruction of tension members.

FIG. 19 is a side view of the blade of FIG. 17, with the movablecontacts attached thereto.

FIG. 20 is a perspective view of the switch blade and supporting rod ofFIGS. 15 and 16.

FIG. 21 is a cross-section along the line 2-121 of FIG. 15 in reducedscale.

Certain words indicating direction, relative position, and the like, areused in the specification and claimed subject matter for the sake ofbrevity and clearness of description. However, it is to be understoodthat such words are used only in connection with the illustrations inthe drawings, and that the parts of the actual embodiments,when in use,may have entirely different directions, relative positions, and thelike. Examples of such words are vertical, horizontal, upper, lower,etc.

FIGS. 1-12 show an extremely small snap switch which has a surprisinglyhigh current capacity. FIGS. 1 and 2 are top and side views of theoutsile of the switch casing drawn to scale on the original patentapplication drawings. The actual dimension for FIG. 1 is .385 inch forthe length. The width is approximately as proportionally shown. For FIG.2 the dimensions are .265 x .385 inch.

Such switch may have an insulative casing 10 having an integral orhomogeneously formed plastic insulative wall or 'wall constructionincluding two opposite first or long sides or side walls 12 and 14, twoopposite end or second or short side walls 16 and 18, and a bottom wall20. These walls may be integrally or homogeneously joined together toform a switch cavity 26 which may be closed by a flat cover 22.

The word homogeneous is used herein in the specification and claimedsubject matter as defined in Websters International Dictionary, G. & C.Merriam Company, Springfield, Mass, as follows: of uniform structure orcomposition throughout, and to be such as produced by the moldingmethods that can be used to produce the casing and cover of thisinvention.

The casing may be a rectangular sided casing in which the side walls 12,14, 16 and 18 and bottom wall 20 may have rectangular outer surfaceswhich may be joined or molded together integrally or homogeneously toproduce the switch cavity 26 with an opening along the uncovered edges19 of the side walls 12, 14, 16 and 18. The cover 22 may have an outerrectangular surface 29. The cover 22 covers the uncovered edges 19 ofsaid side walls 12, 14, 16 and 18 and forms a completely rectangularcovered switch construction. The casing 10 may be molded or formed ofsuitable phenolic material. The cover 22 may be molded or formed of anysuitable material. For example, if desired, the cover may be made of anysuitable transparent moldable material, such as Lexan, which is atransparent polycarbonate. This permits viewing of the switch conditionat any time through such cover.

The walls 12, 14, 16, 18 may have uncovered edges 19 which may becovered and uncovered by means of the cover 22. The cover 22 may besecured to the walls 12, 14, 16 and 18 by the hook construction 23 to befurther described.

Before the cover 22 is placed over the switch cavity 26, a switchconstruction 28 is placed in the cavity 26 in such a manner that theswitch parts can be properly secured in the cavity 26 by the coveringaction of the cover 22.

The switch construction 28 may include a rigid, straight, flat metalelectrically conductive rod 30 with opposite relatively wide flat sides32 and 34 and opposite relatively narrow edges 36 and 38.

The rod 30 may be embedded in preformed notches 40 and 42 in theopposite side walls 12 and 14 and extends out of the side wall 14, whichwall 14 is substantially relatively thick relatively to the other sidewalls 12, 16 and 18, and bottom wall 20. Suitable fastener casingmounting holes 44 may extend through the wall 14 for mounting the switchon a support panel and the like. The cover 22 may have cover holes 45which align with the casing holes 44. A suitable electrical conductorreceiving opening or fork construction or end 46 is provided at the endof rod 30 for attaching an electrical conductor, if desired. The rod 30has opposite tongue and receiving notches 37 and 39.

A first electrical conductor bar 48 extends out of and is embedded inthe side wall 14 and has a first inward stationary contact elbow 50extending into the switch cavity 26. Another or second electricalconductor bar 52 extends out of and is embedded in and extends out ofthe side wall 14 and has a second contact elbow 54 spaced from the firstelbow 50. These bars 48 and 52 may have ends 46 similar to rod end 46.The bars may also have edges similar to the edges of rod 30. These bars48 and 52 and the rod 30 may each be similarly embedded in preformedseparate notches 53 in wall 14, as shown, and have shoulders 49 to lockthem in place. These bars 48 and 52 and rod 30 have their edgeconstructions arrested by the arresting surfaces 55 of the notches 53.The other edge constructions of the bars 48 and 52 and rod 30 may beprovided with barbs 57 which engage the raised portions 103, 104 and 105of the cover 22 later to be described.

A snap action sheet metal blade 56 has outer flat ribbon shaped tensionmembers 58 and 60 and opposite end 4 cross member 62 and 64 joinedintegrally with the tension member 58 and 60.

The tension members 58 and 60 extend past and outside the rod edges 36and 38.

The blade 56 has a first, or inward, relatively flexible, snap tongue 66with one tongue end 68 integrally connected to the first blade end crossmember 64 and with its other tongue end 70 engaging the rod notch 37.

The blade 56 also has a second, or inward relatively stiff pivot tongue72 with one tongue end 74 integrally connected to the other or secondblade end cross member 62. The other pivot tongue end 75 engages theother rod notch 39.

The blade 66 also has convex surfaced movable contact members 78 and 80on the blade end cross member 64 which alternately engage the stationarycontact elbows 50 and 54.

The flexible snap tongue 66 has opposite longitudinally arcuate edges 82and 84. The stiff pivot tongue 72 has opposite longitudinally paralleledges 86 and 88. These tongues 66 and 72 have many characteristics andadvantages.

For example, the blade 56 of the switch may be an entirely flatridgeless snap action sheet metal flexible blade entirely free ofrelatively sharp right angle stilfening bends or ridges, and having theouter ribbon shaped tension members 58 and 60 joined integrally withblade end cross members 62 and 64. Such blade may have the inwardrelatively flexible longitudinally arcuate edged snap tongue 66, and therelatively stiff longitudinally parallel edged pivot tongue 72. Thecooperation of these two tongues during the snap action of the blade issuch that much less force is required to actuate the blade past thesnapping zone than is required with a substantially parallel sidedflexible tongue.

Said blade 56 may have substantially parallel sided relatively stiffunperforated compression tongue 72 integrally joined to the cross member6-2 and extending and terminating in a stright transverse inner end 75which rocks or pivots in a straight notch 39 in the straight pivot rod30 of the switch.

The relatively flexible compression tongue 66 extends inwardly andterminates in a straight transverse inner end 70 which rocks on thestraight notch 37 on the other side of such pivot rod 30.

Said flexible compression tongue 66 is so shaped that it produces a muchmore evenly distributed stress throughout the length of such flexibletongue. For this purpose, the flexible tongue 66 is provided witharcuate longitudinal edges 82 and 84. These arcuate edges may besymmetrical with respect to each other, and may also be convex orconcave with respect to each other.

The stress distribution throughout such flexible arcuate sided flexibletongue 66 is such that there is a much less flexing force needed to snapthe switch blade past the snap point than is required with asubstantially parallel sided compression flexible member.

A plunger 90 engages the blade end cross member 62 and extends out ofthe side wall 12. The plunger has an enlargement or bead 92 to providesuitable enlarged contact with the cross member 62 and the side wall 12,and to limit upward movement of the plunger 90. The plunger 90 may be ofany desired cross section, such as square, round, or the like.

A compression leaf spring 94 may be V shaped with one edge engaging thecross member 62 and the other end engaging a notch 96 in the wall 14.The spring 94 returns the blade to its upper position in FIG. 4 afterthe blade has been pushed down by the plunger 90 and then released.

The blade 56 snaps down when the plunger is pushed down to move theblade tension members 58 and 60 past the snap point of notch 37.

The notches 37 and 39 are not as wide as the rod side 32 and have endshoulders 98 for preventing undue sidewise displacement of the blade 56.

The holes 44 and 45 may be used to receive mounting screws. The holes 45may be countersunk at one end to receive countersunk screw heads.

It is to be noted that the fastener holes 44 and 45 may receive screwsthat hold the cover 22 against one end of the wall 14 and hold the cover22 against the adjacent ends of walls 112, 116 and 118. This is anadvantageous construction.

The cover may have a rectangular flat outer surface 29. The main part ofits inner surface 100 may be rectangular and fiat. The raised portions101, 102, 103, 104, 105 engage various parts of the casing and preventthe cover 22 from being displaced. This also prevents the hookconstruction 23 from being accidentally unhooked. These raised portionsalso add rigidity to the cover 22. The raised portions 103, 104 and 105are engaged by the barbs 57 of the bars 48 and 52 and rod 30, as shownin FIGS. 5 and 7.

The hook construction 23 has a hook 106 which engages the hook ledge 107at the end of the slanting side 108 of the hook receiving opening 109.

The hook construction or finger 23 normally is not long enough to hookover the ledge 107 when the cover 22 is being applied to cover thecasing. The hook finger 23 is slightly bent or has a bend so that a baror tool 111 may be inserted in the opening 109 to cause the bend to bestraightened sufiiciently to allow the hook 106 to be hooked over theledge 107 while the cover is being applied, as shown in FIG. 6.Thereafter the bar or tool 111 may be removed, and the hook 106 willthen engage the ledge 107, as shown in FIG. 5.

The opening 109 is between the casing openings 44.

The hook receiving opening 109 extends completely through the side wallin which it is located, such as in thicker side wall 14. This providesan uncovered external opening 109A through which the bar 111 and/or areleasing tool may be inserted. Such releasing tool may release the hook106 from the ledge 107 when it is desired to release and remove thecover 22 from the casing 20.

The side walls 12, 14, 16 and 18 have respective substantiallyrectangular outer surfaces 113, 115, 117 and 119. The bottom wall hassubstantially rectangular outer surface 121. The cover 22 has the largesubstantially rectangular outer surface 29 and the smaller substantiallyrectangular edge outer surfaces 123. These substantially rectangularsurfaces 29, 113, 115, 117, 119, 121 and 123 form an outer substantiallyrectangular surfaced casing and cover construction. This constructionmay be made very small in size, as shown in actual scale in FIGS. 1 and2. Such construction may be easily and effectively mounted on anydesired support structure by fasteners, such as screws and the like,which may be inserted through the casing and cover openings 44- and 45,with the heads of the screws engaging the outer surface 29 of the cover22. The screw heads alternatively may be countersunk in the cover 22, ina manner similar to that later described.

FIGS. 13-20 show an extremely small snap switch which has a surprisinglyhigh current capacity. FIGS. 13 and 14 are top and side views of theoutside of the switch casing drawn to scale. The actual dimensions forFIG. 13 are .190 x .385 inch and for FIG. 14 are .260 x .385 inch. Theweight is .57 gram.

Such switch may have an insulative casing 110 having an insulative wallor wall construction including two opposite sides or side walls 112 and114, two opposite end walls 116 and 118, and a bottom wall 120. Thesewalls may be integrally joined together to form a switch cavity 126which may be closed by a fiat cover 122.

The walls 112, 114, 116, 118 may be covered and uncovered by means ofthe cover 122. The cover 122 6 may be secured to the walls 112, 114, 116and 118 by any suitable means, such as by adhesive means, fasteners, andthe like.

Before the cover 122 is placed over the cavity 126, a switchconstruction 128 is placed in the cavity 126 in such a manner that theswitch parts are properly secured in the cavity 126 by the coveringaction of the cover 122.

The switch construction 128 may include a rigid straight, fiat metalelectrically conductive rod 130 with opposite relatively wide flat sides132 and 134 and opposite relatively narrow edges 136 and 138.

The rod 130 may be embedded in preformed notches 140 and 142 in theopposite side walls 112 and 114 and extends out of the side wall 114,which wall 114 is relatively thick relatively to the walls 112, 116 and118. Suitable screw mounting holes 144 may extend through the wall 114for mounting the switch on a support panel and the like. A suitableelectrical conductor receiving opening 146 is provided for attaching anelectrical conductor, if desired. The rod 130 has opposite tongue endreceiving notches 137 and 139.

An electrical conductor bar 148 extends out of and is embedded in theside wall 114 and has an inward stationary contact first elbow 150extending into the switch cavity 126. Another electrical conductor bar152 extends out of and is embedded in and extends out of the side wall114 and has a second elbow 154 spaced from the first elbow 150. Thesebars 148 and 152 may be embedded in preformed notches in wall 114, asshown in FIG. 21, and have shoulders 149 to lock them in place.

A snap action sheet metal blade 156, somewhat similar to blade 56, hasouter flat ribbon shaped tension members 158 and 160 and opposite endcross members 162 and 164 joined integrally with the tension members 158and 160.

The tension members 158 and 160 extend past and outside the rod edges136 and 138.

The blade 156 has an inward, relatively flexible, snap tongue 166 withits tongue end 168 integrally connected to the blade end cross member164 and with its other tongue end 170 engaging the rod notch 137.

The blade 156 also has an inward relatively stiff pivot tongue 172 withone pivot tongue end 174 integrally connected to the other blade endcross'member 162. The other pivot tongue end engages the other rod notch139.

The blade 156 also has convex surfaced movable con tact members 178 and180 on the blade end cross member 164 which alternately engage thestationary contact e1- bows 150 and 154.

The flexible snap tongue 166 has opposite longitudinally arcuate edges182 and 184. The stiff pivot tongue 172 has opposite longitudinallyparallel edges 186 and 188. These tongues 166 and 172 have all of thecharacteristics and advantages heretofore described.

A plunger 190 engages the blade end cross member 162 and extends out ofthe side wall 112. The plunger has an enlargement or head 192 to providesuitable enlarged contact with the cross member 162 and the side wall112. The plunger 190 may be of any desired cross section, such assquare, round, or the like.

A compression leaf spring 194 may be V-shaped with one end engaging thecross member 162 and the other end engaging a notch 196 in the wall 114.The spring 194 returns the blade to its upper position in FIG. 15 afterthe blade has been pushed down by the plunger 190 and then released.

The blade 156 snaps down when the plunger is pushed down in a mannersimilar to the blade '56 heretofore described.

The notches 137 and 139 are not as wide as the rod 132 and have endshoulders 198 for preventing undue sidewise displacement of the blade156.

The blade 156A of FIG. 18 is substantially similar to the blade 156 ofFIG. 17. The blades 156A and 156 may be used in the same switchconstruction of FIGS. 13-16, 20

7 and 21. The main difference between the blades 156 and 156A is thatthe tension ribbon members 158A and 160A remain of uniform thickness fora greater length than the ribbon members 158 and 160. Otherwise the twoblades 156 and 156A are substantially the same.

The holes 144 may be used to receive mounting screws,

as previously described. Such holes may be threaded, as

shown, or unthreaded, if desired. The holes may be countersunk at 145 atone end to receive countersunk screw heads.

Alternatively, the holes 144 may receive screws that fasten the cover122 to one end of the wall 114 and hold the cover 122 against theadjacent ends of walls 112, 116 and 118.

Also, the switch may be simultaneously covered and mounted on a paneland the like by screws or bolts passing through holes 114 and beingscrewed or bolt d on the panel as desired. This simultaneously securesthe cover 122 to the walls 112, 114, 116 and 118, and the casing 110 tothe panel and the like.

While the form of the invention now preferred has been disclosed, asrequired by statute, other forms may be used, all coming within thescope of the claimed subject matter.

A new, useful and unobvious switch, casing, and cover therefor have thusbeen provided by this invention.

What is claimed is:

1. Incombination:

a switch casing having two opposite first side walls, two oppositesecond side walls and a bottom wall joined together to form a switchcavity with an opening along uncovered edges of said side walls;

a rigid .flat metal electrically conductive rod embedded in one of saidfirst side walls with opposite relatively wide flat sides and oppositerelatively narrow edges, said rod having a straight portion extendinginto said cavity and a portion extending out of said one of said firstside walls, said rod having opposite tongue and receiving notches insaid flat sides;

a first electrical conductor bar embedded in and extending out of saidone of said first side walls and having a first stationary contact elbowin said switch cavity;

a second electrical conductor bar embedded in and xtending out of saidone of said first side walls and having a second contact elbow in saidswitch cavity;

a snap action sheet metal blade having opposite outer tension membersand opposite end cross members joined integrally with said tensionmembers, said tension members extending past and outside said rod edges,said blade having a first tongue integrally connected to a first one ofsaid blade end cross members with a first tongue end engaging a firstone of said rod notches, said blade having a second tongue integrallyconnected to the second one of said blade end cross members with asecond tongue and engaging the second one of said rod notches, saidblade having movable contact means on said first one of said blade endcross members alternately engaging said stationary contact elbows;

a plunger passing through one of said side walls and actuating saidsecond one of said blade end cross members;

and a casing cover engaging and closing upon said uncovered edges ofsaid side walls, one of said side walls having a hook receiving openingwith a hook locking ledge, said cover having a hook constructionextending therefrom into said hook receiving opening with a hookengaging and locking with said locking ledge to lock said cover to saidcasing; said hook construction having a bend therein intermediate saidcover and said hook that normally causes said hook to be short of saidledge when said cover member is fully engaged against said uncoverededges of said side walls whereby said bend was temporarily straightenendby auxiliary means to permit said hook to further extend from said coverand reach beyond said ledge for the subsequent engagement and lockingtherewith after said auxiliary means was removed from its straighteningaction on said bend.

2. A combination according to claim 1 in which said one of said firstside walls is a thicker side wall that is substantially thicker than theother side walls.

3. A combination according to claim 1 in which said thicker side wallhas casing fastener holes extending through said thicker side wall andsaid cover has cover fastener holes aligned with said casing fastenerholes for receiving fasteners to attach said casing and cover to asupport structure.

4. A combination according to claim 1 in which said hook receivingopening has a slanting side which is engaged by said hook constructionand flexes said hook construction while said hook construction is beinginserted in said hook receiving opening.

5. A combination according to claim 1 in which said hook receivingopening extends completely through said one of said side walls toprovide an uncovered external opening through which said auxiliary meansis insertable.

6. A combination according to claim 5 in which said auxiliary meanscomprises a tool that is temporarily insertable in said uncoveredexternal opening to aid in straightening said bend to engage said hookledge while said hook construction is being inserted in said hookreceiving opening.

7. A combination according to claim 4 in which said one of said walls isa substantially thicker side wall that is substantially thicker than theother side walls.

8. A combination according to claim 7 in which said casing fastenerholes extend through said thicker side wall and said cover has coverholes aligned with said casing fastener holes for receiving fasteners toattach said combination to a support structure.

9. A combination according to claim 8 in which said hook receivingopening is located between said casing fastener holes.

10. A combination according to claim 1 in which a compression spring islocated in said switch. cavity and urges said second one of said crossmembers toward said plunger.

11. A combination according to claim 1 in which said side walls, bottomwall and cover have outer substantially rectangular surfaces, and saidsubstantially rectangular surfaces form an outer substantiallyrectangular surfaced casing and cover construction.

12. In combination:

a switch casing having side walls and a bottom wall joined together toform a switch cavity with an opening along uncovered edges of said sidewalls;

a switch construction in said switch cavity with a switch actuatingplunger extending out through one of said walls;

one of said side walls having a hook receiving opening with a hooklocking ledge;

and a casing cover engaging and closing upon said uncovered edges ofsaid side walls and having a hook construction extending into said hookreceiving opening with a hook engaging and locking with said lockingledge to lock said cover to said casing, said hook construction having abend therein intermediate said cover and said hook that normally causessaid hook to be short of said ledge when said cover member is fullyengaged against said uncovered edges of said side walls whereby saidbend was temporarily straightened by auxiliary means to permit said hookto further extend from said cover and reach beyond said ledge for thesubsequent engagement and locking therewith after said auxiliary meanswas removed from its straightening action on said bend.

13. A combination according to claim 12 in which said hook receivingopening has a slanting side which is 75 engaged by said hookconstruction and flexes said hook construction while said hookconstruction is being inserted into said hook receiving opening.

14. A combination according to claim 12 in which said hook receivingopening extends completely through said one of said side walls toprovide an uncovered external opening through which a tool isinsertable.

15. A combination according to claim 14 in which said auxiliary meanscomprises a tool that is temporarily insertable through said uncoveredexternal opening to aid in straightening said bend to engage said hookledge while said hook construction is being inserted in said hookreceiving opening.

16. A combination according to claim 12 in which one of said side wallsis a substantially thicker side wall that is substantially thicker thanthe other side walls and has said hook receiving opening.

17. A combination according to claim 16 in which said thicker side wallhas casing fastener holes extending through said thicker side wall andsaid cover has cover fastener holes aligned with said casing fastenerholes for receiving fasteners to attach said casing and cover to asupport structure.

18. A combination according to claim 17 in which said References CitedUNITED STATES PATENTS 3,255,333 6/1966 Schuchard 200-159 3,335,900 7/1967 Mackiewicz.

3,337,702 8/1967 Brevick et a1.

3,412,225 11/1968 Rogers et al.

3,449,534 6/ 1969 Bauer.

ROBERT K. SCHAEFER, Primary Examiner D. SMITH, JR., Assistant ExaminerUS. Cl. X.R.

